Which statement best describes aerotolerant bacteria?

Which statement best describes aerotolerant bacteria?

• A. They require oxygen to grow
• B. They metabolize oxygen to derive energy
• C. They strictly grow only at high oxygen levels
• D. They do not use oxygen but tolerate its presence

Answer: (D)

Aerotolerant bacteria don’t use oxygen to harvest energy, but they can tolerate its presence. Their metabolism is typically fermentative, so oxygen doesn’t drive their respiration and isn’t required for growth. This means they can grow in both oxygen-rich and oxygen-free environments. They often survive in the presence of oxygen because they have some capacity to detoxify reactive oxygen species, even though oxygen isn’t part of their energy-generating pathway. This is why the statement that best describes them is that they do not use oxygen but tolerate its presence.

Aerotolerant bacteria don’t use oxygen to harvest energy, but they can tolerate its presence. Their metabolism is typically fermentative, so oxygen doesn’t drive their respiration and isn’t required for growth. This means they can grow in both oxygen-rich and oxygen-free environments. They often survive in the presence of oxygen because they have some capacity to detoxify reactive oxygen species, even though oxygen isn’t part of their energy-generating pathway.

This is why the statement that best describes them is that they do not use oxygen but tolerate its presence.